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| Scheme of an experiment on tree frog tadpoles, which showed that the vertebrate immune system is, in principle, capable of reacting with the body’s own tissues, but during development it learns not to do this. |
According to this scheme immunological memory PD is created; j unology, Oxford, Eng.
They showed that protection against these two diseases can be transferred from one sick animal to another animal when we pass on serum from those animals, called antibodies. Thus, serotherapy was created, which initiated the healing process in medicine for children with diphtheria throughout the world.
Paul Ehrlich has also stood out in the history of the science of immunology since the turn of the century. He was a born researcher, pursuing a career as a chemist when he began his scientific work with the implantation of the German chemical industry. Responsible for the synthesis of the first biological dyes, he created methods for staining blood cells, where he was able to distinguish neutrophils, eosinophils and basophils, and then discovered the mast cell in the tissue. Ehrlich was interested in the specifics of immunological phenomena, the ability to differentiate the mechanisms of active and passive immunization, demonstrating to the scientific community that in the process breastfeeding Antibodies are transferred from mothers to their children.
One of them stimulates a specific immune response and forms a fairly long-term immunological memory to any specific antigens.
The theory of clonal selection provides a conceptual basis for understanding the cellular mechanism of immunological memory. In the peripheral lymphoid tissues of an adult animal, populations of T and B lymphocytes simultaneously contain cells that are at least three discrete stages of differentiation: precursor cells, memory cells and effector cells.
Modern Immunology is born in a complex process of transformation of science and medicine. Various studies of the mechanisms of the immune system, aimed at assembling its biochemical and genetic components, are generating a rapid development in understanding the biological mechanisms of organisms. Therefore, there is a big challenge for discovering treatments for infections, understanding the processes of neoplasia and more. complex task to prevent these diseases through a commitment to developing new vaccines in the near future.
It consists of the study of the immune response, that is, the study of the mechanisms by which the body has the ability to recognize, neutralize, metabolize and eliminate heterologous substances, and become resistant to reinfection. This process occurs with or without tissue damage.
Due to this unnatural path and the dynamics of the entry of antigens into the body, the emerging immune response and immunological memory are significantly lower than with vaccination with live vaccines.
Immunological memory is the body’s ability to provide an accelerated and more effective immune response when an antigen re-enters the body. The basis of immunological memory are memory T and B cells, which are formed during the primary immune response, but do not take part in it. When the antigen re-enters the body, memory cells quickly turn into effector cells.
Humans maintain direct contact with a large number of organisms with highly diverse biological characteristics, many of which can cause focal or generalized physiological imbalances that give rise to disease states. Through immune surveillance, the body maintains its integrity by acting against aggressive agents and endogenous or exogenous substances. To do this, a person uses different defense mechanisms. Various mechanisms are based on the recognition of the self and the self, causing an immune process against the non-self.
Many invertebrates have the ability to reject xenogeneic and even allogeneic transplants. However, their rejection reactions are clearly slower, and their immunological memory is more short-lived than in vertebrates.
Thus, the network of these cells represents a kind of repository of antigens. This structure ensures the long-term presence of antigens in the follicles, which is reflected in the maintenance of immunological memory.
It is recognized that any molecule and structure created at the same time as the maturation of the immune system, thus male sperm will be recognized as not corresponding to the male body, since its morphogenesis occurs only during and after puberty, when the immune system is already fully formed. This process causes male sterility in many men when the blood egg barrier is destroyed.
The mechanism for recognizing self and non-self can be non-specific or specific. There may be situations where the immune system confuses itself and acts against itself, in these cases autoimmune diseases. Immunological reactions can be initiated in cases of fusion of organisms, cases of transfusion and transplantation. A specific immune response against an aggressor is carried out through the participation of cellular agents and humoral agents.
The development, creation and production of live vaccines does not require expensive equipment and an understanding of the subtle mechanisms of patho- and immunogenesis. Modification of the disease process itself reproduces all the mechanisms of natural immunogenesis and the formation of immunological memory.
It has as its main characteristic the descriptor power to be a specific memory mechanism. Upon first contact with an aggressive agent, the body produces an immune response after a certain period of contact. During this period, the aggressor in the body proliferates, causing the disease state. But after the immune response is triggered, the criminal is neutralized and eliminated. As a result, we have a state of resistance to reinfection. Thus, in close contact, the body activates the immune response faster and more effectively, preventing the proliferation of the aggressive agent, preventing the disease state.
Cells of the immune system, upon contact with a foreign antigen, are able to remember it and, when they encounter it again, often give a stronger reaction. Immunological memory is fixed for years, often for life. It is stored either in long-lived lymphocytes, or is inherited by the descendants of trained lymphocytes.
Concepts related to immunological infection
This is the implantation, growth and spread of aggressive creatures in the host's body, which leads to its loss. Inflammation: a protective reaction of tissue in relation to the presence of an aggressive agent. Infectious Agent: Characteristic of an invader that has the ability to infect. Pathogenicity: The ability of an offending agent to cause disease. Virulence: the ability to cause serious or fatal disease. Immunogenic potency: the ability of an aggressor to be perceived and elicit an immune response in the host.
In Fig. Figures 30.6 and 30.7 show the transformation of a virgin B cell into an active plasma cell. At the same time, memory cells are formed from virgin cells. Immunological memory B cells differ from primary active B cells in that they begin to produce IgG earlier and have higher affinity antigen receptors due to selection during the primary immune response. This is due to increased hypermutation of variable regions of immunoglobulins in immunological memory B cells.
This is the body's natural defense. This is a battalion of cells specialized in identifying and destroying all foreign microorganisms that enter the body. As soon as an infectious organism enters the human body, the first to react are macrophages, which attack the intruders.
The remaining invaders serve as a signal for T cells to order B cells, as members of the defense system, to begin producing antibodies. Antibodies attach to the invaders and signal phagocytes to destroy them. From there, all defenses work in the fight against this disease. Once the infection is over, the body is given immunity against the evil. Of course, we must suffer from illness in order to achieve natural immunity. But the immune system, being a specialist in eliminating infections, does not always benefit from this disease.
This was the situation by the beginning of the 70s, and soon a discovery occurred in immunology, which in terms of consequences can only be compared with the discovery of the thymic system of lymphocytes. At first, the studies were puzzled by the fact that the introduction of an antigen directly into the thymus does not, as expected, cause an increase in the immune response or rapid formation of antibodies, but on the contrary, the body becomes less sensitive to subsequent injections of the same protein. What is it, negative immunological memory, immunity with a minus sign. Then it turned out that if lymphocytes from animals that are not reactive to one or another antigen are introduced into a normally reactive animal, then their previously vigorous reaction in the eyes weakens or is completely suppressed.
It includes the defenses normally available to the host to prevent the implantation of an infectious agent. Natural resistance can occur individually or as a form. So, for example, in relation to the tuberculosis bacillus, a person has some resistance to infection. Not every child who comes into contact with the tuberculosis bacillus becomes ill, even without being insured against the aggressor. The most susceptible will get very sick upon first contact, while the more resistant will only get tuberculosis infection but not the disease upon repeated contact.
The immune response begins by binding of the antigen to the receptors of B lymphocytes, and possibly also to the receptors of T cells. Binding of the antigen apparently triggers the division of B cells, from which, through several successive divisions, plasma cells are formed, characterized by high secretory activity and accumulating in various lymphatic tissues. In addition, B cells serve as precursors of the so-called immunological memory cells - long-lived lymphocytes that can quickly proliferate after many years when they encounter a given antigen again.
In this case, the bacillus remains in a state of latent microbial or minimal chronic infection, which causes reactions in the body that guarantee a certain degree of immunity. This is a special state of defense that develops in the body as a result of a previous attack by an infectious agent.
A person is surrounded by a large number of infectious agents: viruses, bacteria, fungi, protozoa and parasites and multicellular parasites. Because these organisms present very differently, there is a need for a wide range of immune responses to combat each type of infection.
Immunological memory. When encountering an antigen again, the body forms a more active and rapid immune response - a secondary immune response. This phenomenon is called immunological memory.
Immunological memory has a high specificity for a specific antigen, extends to both the humoral and cellular immunity and is caused by B and T lymphocytes. It is formed almost always and persists for years and even decades. Thanks to it, our body is reliably protected from repeated antigenic interventions.
External Defensive. Most infectious agents encountered by individuals do not penetrate the body surface due to the difficulty posed by the many biochemical and physical barriers that are part of the body's nonspecific resistance.
The defense mechanisms used during the external defense phase, before the aggressor enters the body, can be divided into three classes. Physical: desiccation, extreme pH, epithelial barriers and fluid flow. Chemicals: lysozymes, acidic fatty acids, proteolytic enzymes. Biological: competition of local flora.
The phenomenon of immunological memory is widely used in the practice of vaccinating people to create intense immunity and maintain it at a protective level for a long time. This is accomplished by 2-3-fold vaccinations during primary vaccination and periodic repeated injections of the vaccine preparation - revaccinations.
However, the phenomenon of immunological memory also has negative aspects. For example, a repeated attempt to transplant tissue that has already been rejected once causes a quick and violent reaction - a rejection crisis.
Entry sites and their protective mechanisms. Lysozyme in tears and other secretions. Removes particles by rapidly passing air through turbocharged bones. Mucus and eyelashes in the respiratory tract Skin - physical barrier, fatty acids and commensals. Digestive acids Rapid change in intestinal pH Intestinal dinosaurs Lower urinary tract flow and female reproductive organ commensals.
Gut eaters help with the digestion process and the formation of fecal cake. When there is a temporary absence of intestinal flora, there is difficulty in the formation of fecal cake and the invasion of other bacteria that cause diarrhea. Attackers who cross the outer barrier will now be attacked by the immune system. Immune responses fall into two categories: the innate immune response, or first line of defense, and the adaptive immune response, or second line of defense.
Immunological tolerance is a phenomenon opposite to the immune response and immunological memory. It is manifested by the absence of a specific productive immune response of the body to the antigen due to the inability to recognize it.
In contrast to immunosuppression, immunological tolerance involves the initial unresponsiveness of immunocompetent cells to a specific antigen.
The innate immune response or first line of defense. It acts on the body nonspecifically and does not change with repeated exposure to the aggressor. May change due to environment: age factors; genetic; nutrition; hygienic; Sanitary, hygienic and psychological services. This first line of defense occurs through the cells that make up immune system, as well as through humoral factors.
Cells associated with the innate immune response. It is an important group of leukocytes, phagocytic cells such as monocytes, macrophages and polymorphonuclear neutrophils and eosinophils. These cells bind to microorganisms, engulf these agents and destroy them. They act quite primitively, without affecting specificity or memory.
Immunological tolerance is caused by antigens, which are called tolerogens. They can be almost all substances, but polysaccharides are the most tolerogenic.
Immunological tolerance can be congenital or acquired. Acquired tolerance can be active or passive. Active tolerance is created by introducing a tolerogen into the body, which forms specific tolerance. Passive tolerance can be caused by substances that inhibit the biosynthetic or proliferative activity of immunocompetent cells (antilymphocyte serum, cytostatics, etc.).
Phagocytosis: Living cells have the ability to engulf particles through an active process that involves the formation of plasma membrane extensions and cytoplasmic vesicles containing intertwined material. This process is usually called endocytosis, which is divided into phagocytosis and pinocytosis. The mechanism is initiated by the adhesion of the particle to the cytoplasmic membrane, followed by invagination, which gradually deepens and eventually internalization of the particle in the cytoplasmic vacuoles, while healing of the cytoplasmic membrane continues at the level of the invagination point.
Immunological tolerance is specific - it is directed towards strictly defined antigens. According to the degree of prevalence, polyvalent and split tolerance are distinguished. Polyvalent tolerance occurs simultaneously to all antigenic determinants that make up a particular antigen. Split or monovalent tolerance is characterized by selective immunity to some individual antigenic determinants.
Phagocytosis is the most primitive form of defense. These single-celled creatures had it only as a form of nutrition and protection, and multicellular creatures had a fundamental process of cleansing the body, either by removing internally generated waste, or by removing foreign bodies of any kind, including microorganisms.
Blood monocytes histiocytes are connective tissue macrophages derived from blood monocytes and migrate into tissues that are contained in the alveoli macrophages microglia endothelial cells intensively phagocytic capacity lining the blood sinusoids of the liver, spleen, bone marrow and lymph cells primitive reticular structures of lymphoid tissue.
The mechanisms of tolerance are diverse and not fully deciphered. There are three most likely reasons for the development of immunological tolerance:
1. Elimination of antigen-specific lymphocyte clones from the body.
2. Blockade of the biological activity of immunocompetent cells.
3. Rapid neutralization of antigen by antibodies.
The phenomenon of immunological tolerance is of great practical importance. It is used to solve many important medical problems, such as organ and tissue transplantation, suppression of autoimmune reactions, treatment of allergies and other pathological conditions associated with aggressive behavior of the immune system.
